Sounds like the dreaded overdrive solenoid failure mode. The J-type OD was less prone to it but nothing is forever.
Definitely do an oil change, screen cleaning and refill first. While you are down there give the wire to the solenoid a critical look. Pinch the wire double with your fingers, if the insulation cracks or flakes off it got very hot from the solenoid overheating, definite trouble. You will need to consult your manual (in your hip pocket, right?) for instructions on how to replace it and adjust it to the correct throw length once installed (extremely important!).
Hopefully, you will find a slightly low oil level and kaka on the screen so a good clean and refill will fix it.
Mike!